The present invention relates in general to a method of attaching fiber sheet, cloth and non-woven cloth (mat, etc.), containing carbon fiber, glass fiber or similar materials, to a surface of a concrete structure, then having said fiber impregnated with a matrix resin and cured to form a fiber reinforced plastic. It relates particularly to a primer for lining a wet concrete surface, and a lining method and a reinforcing method, which permit attachment of the fiber sheet, cloth, etc., which have a satisfactory adhesion strength, to a wet concrete surface of water containing, concrete structures, such as bridge girders for river bridges, road tunnels, or quay walls in harbors.
Attempts have been made to reinforce concrete structures with a reinforced fiber sheet comprising reinforcing fibers attached unidirectionally to a supporting sheet with an adhesive layer. The reinforced fiber sheet is attached to a surface of concrete structures such as bridge girders for automobile and railway bridges, and the reinforcing fibers are impregnated with a matrix resin and cured to form a fiber reinforced plastic. The applicant of the present invention has previously proposed a reinforced fiber sheet suitable for such purpose and its manufacturing method as well as a method of reinforcing a structure using a reinforced fiber sheet (Japanese Patent Application Laid Open Nos. 3-222734 and 3-224901).
The impregnation of a matrix resin and the attachment of a reinforced fiber sheet described above may be done either by impregnating the reinforcing fibers of the reinforced fiber sheet with the matrix resin beforehand at a reinforcement work site and then attaching the reinforced fiber sheet on a concrete surface of a structure, or by coating a concrete surface with the resin, fixing the reinforced fiber sheet thereon and then pressing the same from above to impregnate the resin into the fibers. Another process which may be used, treats the supporting sheet to allow a resin to penetrate the sheet. A primer is spread over a concrete surface, and the reinforced fiber sheet is attached. Later that resin is applied over the supporting sheet for impregnating the resin into the fibers.
These processes have the following advantages: (1) resin can be impregnated into reinforced fiber materials at a reinforcement work site for reinforcement of concrete structures with good workability; (2) heat curing, which requires manpower at a reinforcement work site, is not necessary, and with the use of the room temperature curing resin, the curing and reinforcement can be easily done by leaving the work as it is; and (3) the reinforcement with a fiber reinforced plastics can be made not only on flat concretes surfaces, but also on curved concrete structures.
To obtain sufficient reinforcement through formation of a reinforced fiber plastic using the reinforced fiber sheet mentioned above, it is important to attain good adhesion of the reinforced fiber sheet on the concrete surface.
However, on water containing, wet concrete surfaces, like a bridge girder of a bridge over a river, a road tunnel, or a quay wall in a harbor, the reinforced fiber sheet cannot be fixed satisfactorily with any of the methods of impregnation of a matrix resin and fixation of a reinforced fiber sheet mentioned above because of the presence of water. Thus, the use of reinforced fiber sheet sometimes does not produce the desired reinforcement.
The above mentioned problems occur not only during reinforcing a concrete structure with the reinforced fiber sheet, but also during waterproofing work of a concrete structure and repair and maintenance of damaged places using the reinforced fiber sheet.